Along most highways there are hazards which present substantial danger to drivers and passengers of vehicles if the vehicles leave the highway. To prevent accidents from a vehicle leaving the highway, guardrails are often provided along the side of the highway. Experience has shown that guardrails should be installed such that the end of the guardrail facing the flow of oncoming traffic does not present another hazard more dangerous than the original hazard requiring installation of the guardrail. Early guardrails often had no protection at the end facing the oncoming traffic. Sometimes impacting vehicles became impaled on such guardrail ends causing extensive damage to the vehicle and severe injury to the driver and/or passengers. In some reported cases, the guardrail penetrated directly into the passenger compartment of the vehicle fatally injuring the driver and passengers.
Various guardrail designs and end terminal assemblies have been developed to minimize the consequences resulting from impact between a vehicle and the end of a guardrail. These designs include tapering the end of the guardrail into the ground to eliminate potential contact with the end of the guardrail. Other types of end terminal assemblies include breakaway cable terminals (BCT), vehicle attenuating terminals (VAT), the Sentre end treatment, and breakaway end terminals (BET).
It is desirable for an end terminal assembly to be usable at any end of a guardrail as a means of both attenuating a head on impact as well as providing an effective anchor for an impact along the side of the guardrail downstream from the end terminal assembly. Examples of such end terminal assemblies are shown in U.S. Pat. No. 4,928,928 entitled Guardrail Extruder Terminal, and U.S. Pat. No. 5,078,366 entitled Guardrail Extruder Terminal. Both patents are incorporated by reference for all purposes within this application.